1. Field of the Invention
This invention relates to a data packet router for a mobile communication device. A data packet router is hardware or software which routes data packets (e.g. IP packets) to a device with a specific address. A mobile computing device includes without limitation handheld computers, laptop computers, mobile telephones, personal organisers and wireless information devices.
2. Description of the Prior Art
Mobile communication devices typically connect to WANs (such as the internet) in one of two ways. First, some devices are able to connect to the internet over the PSTN using an internal modem. For example, a laptop computer may have an internal modem allowing it to access the internet over the PSTN. This approach to accessing the internet has several disadvantages—(i) it requires the user to locate a spare telephone socket for a telephone jack leading from the laptop and (ii) the internal modem adds cost. The second approach is to use any long-range wireless communication capabilities (e.g. GSM or UMTS etc.) that the device itself may posses to reach a gateway (e.g. a WAP gateway) which is connected to the internet. However, using a wireless bearer such as GSM may be unreliable and slow. High bandwidth systems such as UMTS are likely to be costly.
There has also been much speculation about allowing mobile communication devices to access a wired gateway or access point to the internet so that, when in range of such a gateway, they can take advantage of the lower data access costs, high bandwidth and reliability of wired networks. For example, it has been suggested that a GSM or UMTS mobile telephone might also be enabled with a short range wireless capability, such as Bluetooth™, so that when it came into range of an access point (a Bluetooth “pod”) connected by wire to the internet, it could preferentially connect to the internet via the Bluetooth pod as opposed to using a GSM WAP connection. When out of range, it would revert to the conventional GSM WAP approach. Similarly, it is also possible for 802.11 enabled mobile communication devices to dial into a 802.11 access point for a LAN; the access point is typically a stand alone unit comprising a radio transceiver; it may itself be directly wire connected to the internet, or may be connected to a PC which is wire connected to the internet. The 802.11 enabled mobile communication device can then access the internet via the access point. But this approach requires additional infrastructure investment in new hardware access points and hence fails to filly exploit, at low cost, the existing PC based infrastructure that exists in most organisations.
Conventional PCs can connect to WANs such as the internet either by directly dialing out over a PSTN land line via an internal or external modem or connecting to a server over a LAN which in turn can either dial out over a PSTN land line using a modem or is permanently connected over a dedicated line. Many businesses have spent considerable sums in developing LANs and server gateways to the internet and these are now commonplace parts of a computer or communications infrastructure. Using this infrastructure to allow mobile communication devices to access the internet is a compelling concept. The prior art suggests that it is possible for a mobile communication device to access the internet via a PC itself connected to the internet (e.g. directly or via a server)—i.e. to use the ubiquitous PC itself as the access point. Reference may for example be made to WO 01/90853 and EP 1028560. However, these disclosures provide few details on how to actually implement such a system.
It is also possible for remote PCs to dial into a server over a PSTN connection using Microsoft Remote Access Server (RAS). But this in essence amounts to allowing an external device to look into an organisation's computer infrastructure, as opposed to using that existing infrastructure to enable a wireless computing device to look outside to the internet via RAS. In theory, RAS can be used to allow a mobile computing device to access the internet via a PC running RAS, but it is difficult to configure and inflexible.